1. Technical Field
The present disclosure relates to a radar apparatus mounted on a moving body such as a vehicle.
2. Description of the Related Art
A radar apparatus that receives a reflection signal from a target (hereinafter also referred to as an object) using a plurality of reception antennas included in an array antenna and that estimates the direction of arrival of the reflection signal from the object within a wide-angle range on the basis of phase differences between the reception signal received by the reception antennas is known.
In order to estimate the direction of arrival of a reflection signal from an object using an array antenna, amplitude and phase deviations between reception antenna systems caused in antenna elements included in the reception antenna systems, radio frequency (RF) circuits that handle high-frequency signals, and analog baseband circuits that handle baseband signals need to be corrected (hereinafter referred to as reception array correction). A digital beamforming (DBF) radar apparatus disclosed in Japanese Unexamined Patent Application Publication No. 2001-166029 is an example of the related art for reception array correction.
The DBF radar apparatus disclosed in Japanese Unexamined Patent Application Publication No. 2001-166029 detects phase differences of a digital reception signal between a reference element antenna and other element antennas and estimates, on the basis of detected phase differences between the reference element antenna and other element antennas belonging to the same group as the reference element antenna, phase differences between the reference element antenna and element antennas belonging to other groups. The DBF radar apparatus compares the estimated phase difference and the detected phase difference for each element antenna belonging to another group to calculate a phase correction value, and corrects the phase of the digital reception signal using the phase correction value. As a result, the DBF radar apparatus can calculate, for each element antenna, a phase correction value for offsetting a phase lead or lag due to changes in the temperature of a low-noise amplifier or temporal changes. Accordingly, the DBF radar apparatus can suppress deterioration of the accuracy of estimating the direction of arrival of a reflection signal from an object and deterioration of target direction estimation performance.